Does apixaban reduce stroke or systemic embolism and major bleeding compared to warfarin in patients with atrial fibrillation, irrespective of concomitant aspirin use?
Apixaban maintains its efficacy and safety benefits over warfarin in patients with atrial fibrillation, regardless of whether they are taking concomitant aspirin.
AIMS: We assessed the effect of concomitant aspirin use on the efficacy and safety of apixaban compared with warfarin in patients with atrial fibrillation (AF). METHODS AND RESULTS: In ARISTOTLE, 18 201 patients were randomized to apixaban 5 mg twice daily or warfarin. Concomitant aspirin use was left to the discretion of the treating physician. In this predefined analysis, simple and marginal structured models were used to adjust for baseline and time-dependent confounders associated with aspirin use. Outcome measures included stroke or systemic embolism, ischaemic stroke, myocardial infarction, mortality, major bleeding, haemorrhagic stroke, major or clinically relevant non-major bleeding, and any bleeding. On Day 1, 4434 (24%) patients were taking aspirin. Irrespective of concomitant aspirin use, apixaban reduced stroke or systemic embolism with aspirin: apixaban 1.12% vs. warfarin 1.91%, hazard ratio (HR) 0.58, 95% confidence interval (CI) 0.39-0.85 vs. without aspirin: apixaban 1.11% vs. warfarin 1.32%, HR 0.84, 95% CI 0.66-1.07; P interaction = 0.10 and caused less major bleeding than warfarin (with aspirin: apixaban 3.10% vs. warfarin 3.92%, HR 0.77, 95% CI 0.60-0.99 vs. without aspirin: apixaban 1.82% vs. warfarin 2.78%, HR without aspirin 0.65, 95% CI 0.55-0.78; P interaction = 0.29). Similar results were seen in the subgroups of patients with and without arterial vascular disease. CONCLUSION: Apixaban had similar beneficial effects on stroke or systemic embolism and major bleeding compared with warfarin, irrespective of concomitant aspirin use.
Alexander et al. (2013) studied this question.